Circular or barrel terminal systems for carrying moderate to high electrical current are known. These systems are typically used in automotive multi-pin harnessing systems to convey electricity to fans, power windows, power locks, lights, and other electrical devices.
As shown in the sectional views of FIGS. 1 and 2, prior art connector systems involve male pins and cooperative pin-receiving members mounted within respective plastic housings which mate together. Each of the respective plastic housings contain a plurality of channels for receiving male pins and corresponding pin-receiving members. The male pin member is comprised of a pin connected to a narrow or "neck-down" region conformed for cooperative engagement with a locking finger disposed within the channel of the plastic housing. The pin member neck-down region is connected in turn to crimping tabs; one opposed pair of crimping tabs are crimped around the wire, and another pair are crimped around insulation and/or around environmental seals made of elastomer or rubber.
The pin-receiving member of the prior art connector assembly, as shown in FIGS. 3 and 4, comprises pin-receiving contacts, a similar narrow or neck-down region conformed for cooperative engagement with a locking finger of the respective plastic housing, and two sets of opposed crimping tabs, one set for crimping the wire and the other for crimping insulation and environmental seals. The pin-receiving contacts are cylindrical in shape and formed out of a stamped piece of metal. The connector has opposed tinned contact beams for receivably engaging the pin. A shroud tube or sleeve is used to protect the outer ends of contact beams.
The tinned surface of the contact beams renders the connector unreliable for low-current, low-voltage applications which are typical of much of the electronics used in automobiles, such as sensors, computers, and integrated circuits. The tin is susceptible to corrosion, and therefore low-impedance signals are jeopardized by static and discontinuity. Moreover, because the surface area of connectors used for power applications must be large so as to dissipate heat generated by high current, it would be expensive to gold-plate contact beams in an attempt to adapt the connectors to signal-carrying applications. On the other hand, terminals specially designed for transferring low-current signals do not lend themselves to high current applications due to their increased cost and diminished electrical and thermal characteristics when high-current is transferred.
Many prior art pin connectors are not suitable for carrying high current. The hollow neck-down region which provides clearance for a locking finger of the plastic housing is characterized therein by a reduction in material cross-section which proportionally decreases the current-carrying ability of the connector.
Some applications require that both high-current and low-current terminals be used side-by-side in one system. Using different types of connectors or styles of terminals can become costly and complicated. Much confusion results because the connectors may have to be removed from the plastic insulative housings to determine whether they are of the signal-transferring or power-transferring type.